Radiation therapy has a long history of providing increased local and regional control of disease when used after surgery for malignancies of the brain, head & neck, lung, breast, stomach, pancreas, colon, rectum, uterus, cervix, prostate, skin, esophagus, kidney, bladder, ovary and soft tissues (sarcomas). Traditionally, the majority of radiotherapy was delivered via an external radiation source, called external beam radiotherapy or EBRT. About 90% of radiotherapy is given via EBRT. The remainder is given via techniques where a radioactive isotope is placed within close proximity to a targeted tumor, called brachytherapy.
Intraoperative radiotherapy (IORT) is a subspecialty in which the radiotherapy is given at the time of surgery. Its primary advantage is the ability to surgically remove organs-at-risk from the post-operative field during treatment, enabling higher doses to be given safely. IORT has been in use for many years at specialized facilities and has a wealth of clinical data to support its safety and efficacy. Both EBRT and brachytherapy protocols have been developed for IORT. A disadvantage of IORT is the tremendous capital costs associated with setting up a program, since a fully-equipped operating room (OR) and a shielded radiotherapy delivery room must be functionally united. This has limited the expertise to select centers.
Two concomitant developments have created an opportunity to overcome the current limitations of IORT. One is the development of electronic brachytherapy. A catheter-based radiotherapy system that produces ionizing radiotherapy from a very small source. It can effectively reproduce radiotherapy fields that were generated with seed-sized isotopes. Its treatment energy is low enough that expensive shielding is not required, and as it is not radioactive (when the machine is off), expensive procedures and protections are not required. This has just recently been FDA approved in for treatment of breast and skin cancers and has not been used intraoperatively yet as of the time of the filing of this document.
The second development is surgical robotics. A success story developing over the previous decade, surgical robots have facilitated more and more minimally invasive procedures, including oncologic resections. The rapid recovery time and shortened hospital stays have been well-received in all applications. Prostatectomies and hysterectomies comprise the majority of oncologic surgeries, though this is evolving. Patients are evaluated for post-operative radiotherapy in the same manner after either a robotic or traditional resection.
Combining the two technologies in the IORT setting would realize several practical advantages. Electronic brachytherapy does not require significant capital costs. It can be applied in ORs in use today. And the robotics would maintain the minimally invasive surgical advantage. This is clearly of interest to many.
The manner in which the systems can be integrated, however, is not particularly clear. Delivering radiotherapy at the time of resection requires precise calculations to be done in “real time” and these systems do not exist for electronic brachytherapy. Currently, balloon applicators are used, primarily because the dosimetry is simple. Balloon applicators, however, do not facilitate customization of the radiotherapy fields. It is possible that other traditional applicators can be used, though none of these would enable minimally invasive surgery, real-time dosimetry, and customization of the radiotherapy fields.
Therefore there is a need for a set of applicators that would satisfy both requirements, namely, be minimally invasive and permit real-time dosimetry, as well as customization of the radiotherapy fields. It is also contemplated, that the present invention can be used in non-robotic environments and achieve advantages over previous devices.